RESUMEN
@#ObjectiveTo investigate the effect of hyperlipidemia on monophasic action potential and calcium current of heart in rabbits.Methods24 rabbits were divided into the high cholesterol group (n=12) and control group (n=12) and fed with high cholesterol forage and standard forage respectively for 10 weeks. Electrocardiograph, ventricular fibrillation threshold and the level of serum lipid were examined. Whole-cell patch clamp technique was used to record I_ Ca-L.ResultsIn high cholesterol group, the serum cholesterol level was higher than the control group ( P<0.01), ventricular fibrillation threshold (10.2±1.7 V) lower than that of the control group (13.9±1.3 V)( P<0.05), MAPD90 displayed more significant rate-dependent prolongation. At cycle lengths of 1500 ms, MAPD90 was 358±18 ms in the high cholesterol group, while it was 277±20 ms in the control group. The densities of ICa-L were larger in the high cholesterol group (14.7±0.8 pA/pF) than that in the control group (10.9±1.1 pA/pF)( P<0.01).ConclusionHypercholesterolemia can produce cardiac electrical remodeling, including increased ICa-L, prolonged repolarization and decreased ventricular fibrillation thresholds.
RESUMEN
In the isolated perfused rat heart, TFH counteracted significantly the arrhythmias caused by perfusing with a solution without oxygen; increased ventricular fibrillation threshold markedly and showed a good dose-effective relation; prolonged the P-R period of electrocardiogram and decreased the heart rate and fell the amplitude of cardiac contraction markedly; and counteracted significantly the decrease of the heart rate and the amplitude of cardiac contraction caused by perfusing with a solution without oxygen. In the isolated guinea pig left atrium, TFH prolonged the function refractory period slightly. In the isolated guinea pig right atrium, TFH increased the accumulated dose of aconitine inducing arrhythmias.